Is setting "rgbd_cameras" to 0 a "hidden" feature?

[hagenoneill]

Hello,

I recently discovered that setting "rgbd_cameras" to 0 causes rtabmap_slam and rtabmap_odom to subscribe to the "rgbd_images" topic where I can use the rtabmap_sync rgbdx_sync node to send a combined rgbd image.

However, when i try to look up documentation for this feature here this isn't mentioned.

I was wondering if anyone knew of any pros/cons of syncing multiple rgbd images this way instead of setting "rgbd_cameras" to 2 and feeding them into the topics "rgbd_image0", "rgbd_image1", etc.

Is there a reason it isn't documented? Is it identical under the hood?

Thanks!

[matlabbe]

Hi, the documentation was missing. I just updated it.

With rgbdx_sync, you can sync up to 8 cameras. With direct sync in rtabmap or odometry nodes, you can sync up to 5 or 4 cameras respectively.

Usin rgbdx_sync can be useful if you want to sync a LiDAR running a lower frame rate in rtabmap node, so you can pre-sync all cameras at 30 Hz with rgbdx_sync, then sync with lidar at 10 Hz in rtabmap node.

Other than that, there are no other advantages of rgbdx_sync.

cheers,
Mathieu

[hagenoneill]

Awesome, thanks for the documentation!